Pavement



0st.- 1950 K. E. MCCONNAUGHAY 2,524,395

PAVEMENT Filed Jan. 22, 1945 IN V EN T OR. Kama/Em f. fffommuam;

Patented Oct. 3, 1950 UNITED STATES PATENT OFFICE Kenneth E. McConnaughay, West Lafayette, Ind. Application January 22, 1945, Serial No. 573,938

My invention relates to pavements, embankment facings, and other slabs formed of Portland-cement concrete and provided with expansion joints. It is the object of my invention to improve the quality of such expansion joints and to reduce the cost of providing them in concrete slabs.

In carrying out my invention, I spread a semifluid concrete mix to form a continuous slab; and before the concrete has set I mix into it along the line of the desired expansion joint a proportion of liquefied bitumen suffiicient to change the character of the concrete from a cement-bound concrete to a bitumen-bound concrete.

The accompanying drawing illustrates my invention: Fig. 1 is a vertical section through a concrete slab longitudinally of an expansion joint showing one form of apparatus which may be employed in producing the joint; and Fig. 2 is a vertical section On the line 2-2 of Fig. 1.

In practicing my invention, I first prepare in any suitable manner the surface upon which the concrete slab is to be laid, and upon such surface I spread a concrete mix of any desired consistency. The mix may be spread and leveled by hand or by any suitable machine, as the means employed in spreading the mix are immaterial to the practice of my invention. In spreading the mix, it is distributed continuously and Without any interruption for the provision of expansion joints. The spread, slab-forming mix is indicated in the drawing by the reference numeral 10.

After the mix has been spread as above indicated, but before it has set, I mix into it along the line of the desired expansion joint a substantial proportion of liquefied bitumen. The means employed in effecting this mixture may take any desired form, that shown in the drawing being merely illustrative. The device shown in the drawing comprises a vertical shaft H which carries at its lower end a series of mixing blades l2. Associated with the shaft II is a conduit l3 through which is supplied the liquefied bitumen employed in forming the expansion joint. With the shaft rotating and with liquefied bitumen being discharged from the conduit l3, the shaft is drawn through the slab l along the line of the desired expansion joint, thus causing the liquefled bitumen discharged from the conduit l3 to be mixed into the concrete as indicated by the stippling in Figs. 1 and 2. If it is desired, any

1 Claim. (C1. 94-18) unevenness produced in the surface of the slab as a result of the passage of the shaft ll may be smoothed as by troweling or in any other suitable manner.

Where the slab I0 is spread and leveled by a finishing machine, the shaft 1 I and the means by which it is supported and moved may be incorporated in such finishing machine. If it is not convenient or desirable to mount the shaft ll upon the finishing machine, it may be mounted in other ways, as upon a broad-tired vehicle. In the latter event, the concrete mix is made relatively stiff so as to be able to support the vehicle without causing any undesirable disfiguring of the surface of the slab.

The depth to which the bitumen is mixed into the concrete of the slab may vary, but I prefer that such depth approximate the thickness of the slab. Accordingly, the drawings show the shaft l2 as extending approximately completely through the slab.

The bitumen employed in forming the expansion joint may be liquefied in any desired way, but I prefer to liquefy it by emulsification by employing a suitable soap or other emulsifying agent promoting the formation of an emulsion of the bitumen-in-water type. For example, I may employ an emulsion containing about 1200 parts asphalt, 800 parts water, 7 parts oleic acid, and 1 part caustic soda. The proportion of emulsion mixed into the slab may vary considerably, but I prefer to supply the bitumen in quantities suflicient to insure that the joint will contain at least 5 per cent of bitumen.

Instead of using asphalt in the material which is mixed into the concrete to form the expansion joint, I may use tar, petroleum wax, or in general any plastic, water-insoluble material capable of being mixed with concrete to form a semiplastic mass. Liquefaction of such material may be obtained with solvents instead of by emulsification.

A joint produced by the method described above is characterized by the fact that it is more or less integral with the slab on each side of it. There is no sharp line or plane of demarcation between the joint and the remainder of the slab such as is present in prior expansion joints of which I am aware. Along each vertical side of the joint there is a layer of substantial thickness in which the proportion of bitumen increases toward the center of the joint. In consequence of this, the tendency of the joint to become separated from the slabs between which it 1185 or to be forced up- REFERENCES orrEn wardly from the space between such slabs is very The following references are of re'cord in the materially reduced. me of this patent:

I claim as my invention: In a concrete slab, an expansion joint integral with the remainder of the slab and comprising UNITED STATES PATENTS a mixture of bitumen with the concrete of the bc Name Date slab, the proportion of bitumen in the mixture ,972 H ltzel Feb. 13, 1934 at the sides of the joint increasing toward the 2,026,983 Plauson Jan. 7, 1936 center of the joint. 10 2 L OmanSky Nov. 12, 1940 KENNETH E. MCCONNAUGI-IAY. 

